Apparatus for testing cigarettes or the like

ABSTRACT

A cigarette testing apparatus wherein each end of the wrapper of a cigarette advancing with a rotary conveyor past a testing station receives a stream of gaseous testing fluid from a conduit which is connected with a source of testing fluid, and wherein a further conduit connects the interior of the wrapper at the testing station with an electropneumatic transducer which generates signals denoting the condition of successively tested wrappers. In order to prevent columns of testing fluid in the conduits from oscillating as a result of abrupt establishment and/or abrupt termination of communication between such conduits and the wrappers of cigarettes moving toward, past and beyond the testing station and from thereby distorting the signals which are generated by the transducer, at least one such conduit admits a stream of fluid into an oscillation-preventing device having an injector nozzle serving to convert the inflowing stream into a coherent laminar flow which traverses, without guidance, a chamber whose interior is maintained at atmospheric pressure, and which thereupon advances toward the testing station or toward the transducer by flowing through an intercepting orifice.

BACKGROUND OF THE INVENTION

The present invention relates to improvements in apparatus for testingcigarettes or analogous rod-shaped articles which constitute or formpart of smokers'0 products. More particularly, the invention relates toimprovements in apparatus for testing cigarettes or analogous rod-shapedarticles (hereinafter referred to as cigarettes) during transport by arapidly advancing conveyor, such as a rotary drum-shaped conveyor whichrotates about its axis and is provided with peripheral flutes oranalogous receiving means wherein the cigarettes are held in parallelismwith the axis of the conveyor during travel toward, through or past andbeyond a testing station.

It is known to test cigarettes or analogous rod-shaped articles of thetobacco processing industry by causing streams of air or another gaseoustesting fluid to flow radially through the wrappers of successivecigarettes and by monitoring the pressure differential between theinterior and the exterior of the wrappers. It is also known to test thewrappers of cigarettes for integrity by monitoring the pressure oftesting fluid which is admitted into one end of the wrapper, bymonitoring the pressure of fluid (if any) which issues from the otherend of the wrapper, and by ascertaining the differential between thepressures of the inflowing and outflowing fluids. The testing fluid canbe caused to flow through the wrappers of successive cigarettes bysuction, or at least one end of the wrapper of the cigarette at thetesting station can be connected with a source of compressed gaseoustesting fluid.

As a rule, the wrappers of cigarettes are tested in the manufacturingmachine itself or in a machine which processes the cigarettes, forexample, in a filter tipping machine wherein plain cigarettes are joinedwith filter mouthpieces to form therewith filter cigarettes of unitlength or multiple unit length. The testing can involve attempts atdetection of open seams, holes, frayed ends of the wrappers, acombination of such defects and/or a monitoring of the porosity ofintentionally perforated portions of the wrappers of plain cigarettes orfilter cigarettes, namely, of wrapper portions which are perforated forthe purpose of admitting relatively cool atmospheric air into the columnof hot tobacco smoke. Many manufacturers of cigarettes demand theutilization of perforated wrappers because they believe that theadmission of cool atmospheric air exerts a beneficial influence upon andreduces the presumably deleterious effects of tobacco smoke upon thehealth of the smoker. In many instances, the testing operation involvesadmission of compressed testing fluid (normally air) into both ends of acigarette and monitoring the drop of pressure (if any) which develops asa result of escape of some testing fluid through the wrapper of thetested article. The differential between the pressure of the admittedtesting fluid and the pressure of testing fluid in the interior of thewrapper of a cigarette at the testing station is indicative of thequality or condition of the tested article. The signals which aregenerated to denote the detected pressure differential are evaluatedand, if warranted, utilized to segregate defective articles fromsatisfactory articles prior to entry of defective articles into the nextmachine, such as a packing machine which normally follows a filtertipping machine. The testing of filter cigarettes in a filter tippingmachine is further indicative of the condition of the uniting band whichis utilized to couple the filter mouthpiece with the tobacco-containingportion, e.g., with a plain cigarette. If the sealing action of theuniting band is unsatisfactory, excessive quantities of testing fluidwill escape in the region where the plain cigarette abuts against theadjacent end portion of the filter.

Cigarettes are tested while advancing at the operating speed of a makingor processing machine. The output of such machines is extremely high;for example, a modern filter tipping machine can turn out well in excessof one-hundred filter cigarettes per second. Therefore, the intervalswhich are allotted for the testing of individual cigarettes in a filtertipping or an analogous machine are extremely short, normally in therange of a few milliseconds. During such extremely short intervals, thepressure of testing fluid which is admitted into the interior of acigarette at the testing station must be built up at both ends of thecigarette, and the signal denoting the drop of pressure as a result ofporosity or defectiveness of the wrapper must be generated within thesame short interval of time, namely, before the pressure of testingfluid is reduced again and not later than when the freshly testedcigarette advances beyond the testing station.

Each application and termination of pressure of testing fluid entailsoscillations of the column of testing fluid in the form of standingwaves in the conduits for testing fluid. Such oscillations of testingfluid are highly likely to distort the results of the testing operation.Therefore, the testing of a preceding cigarette must be followed by aninterval which is long enough to allow the oscillations to fade out,i.e., the column of testing fluid in the conduit or conduits leading toand from the testing station must cease to oscillate before thetransducer which converts pneumatic signals into electrical or othersuitable signals for further processing generates a signal denoting thecondition of the tested article. This entails considerable shortening onthe aforediscussed extremely short intervals of time which are availablefor the testing of successive cigarettes during transport through thetesting station in a modern high-speed cigarette making or processingmachine. The shorter the intervals which are available for actualtesting, the greater is the likelihood of distortion of signals whichdenote the condition of the tested articles. Furthermore, theaforediscussed shortening of extremely short intervals which areavailable for testing of successive cigarettes, namely, a shortening forthe purpose of permitting the oscillations of testing fluid todisappear, reduces the possibility of further increasing the output ofthe machines in which the testing apparatus are used. In other words, ifall other units of a machine for the making or processing of cigaretteswould allow a pronounced increase of the output, for example, to 10,000cigarettes per minute, presently known testing apparatus would preventsuch increase in output because their operation at corresponding speedsof the articles to be tested would be unsatisfactory so that they wouldpermit defective cigarettes to reach the next processing station and/orwould or could cause ejection or segregation of satisfactory cigarettes.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the invention is to provide a testing apparatus forcigarettes or the like wherein the entire interval of dwell of a rapidlyadvancing article at the testing station can be utilized for actualdetermination of the condition of such article.

Another object of the invention is to provide a testing apparatus whichcan properly test the wrappers and/or other constituents of cigarettesor analogous rod-shaped articles in a cigarette making or filter tippingmachine, even if the speed of the machine is increased beyond the speedat which presently known testing apparatus can reliably test successivearticles.

A further object of the invention is to provide a testing apparatuswhich can be installed in existing cigarette making, filter tipping oranalogous machines as a superior substitute for presently known testingapparatus.

Another object of the invention is to provide a testing apparatus whicheliminates oscillations of the column or columns of testing fluid in asimple, inexpensive and space-saving manner.

An additional object of the invention is to provide the testingapparatus with novel and improved means for admitting testing fluid intothe wrappers of successive cigarettes or analogous smokers' articles.

A further object of the invention is to provide a novel and improvedmethod of preventing oscillations of columns of testing fluid inconduits which admit testing fluid to the wrappers of cigarettes oranalogous rod-shaped articles during transport of the articles throughthe testing station.

An additional object of the invention is to provide a testing apparatuswhich is more accurate and more reliable than heretofore known testingapparatus, even if the rate at which the articles to be tested aretransported therethrough greatly exceeds the speed of transportedarticles in conventional testing apparatus.

An additional object of the invention is to provide the testingapparatus with novel and improved means for regulating the flow oftesting fluid between a source of testing fluid and one or both ends ofan article at the testing station.

The improved testing apparatus is utilized to test, at a testingstation, the open-ended tubular wrappers of cigarettes or analogousrod-shaped articles wherein the wrapper surrounds a filler consisting oftobacco and/or filter material. The apparatus comprises conveyor means(e.g., a rotary drum-shaped conveyor having axially parallel peripheralarticle-receiving flutes) arranged to transport a succession of articlestoward, past and beyond the testing station (preferably in such a waythat the articles are transported sideways, i.e., at right angles totheir respective axes), and means for admitting a stream of gaseoustesting fluid (e.g., air) into at least one end of the wrapper formingpart of the article advancing past the testing station with attendantestablishment of a pressure differential between the interior and theexterior of the wrapper. Such fluid admitting means includes a source ofpreferably compressed gaseous testing fluid, conduit means for conveyingtesting fluid between the source and the testing station (i.e., from thesource toward the testing station if the testing fluid is maintained atsuperatmospheric pressure), and means for preventing oscillations oftesting fluid in the conduit means as a result of abrupt admissionand/or abrupt termination of admission of testing fluid into thewrappers of articles at the testing station. The oscillation preventingmeans comprises an injector nozzle receiving the stream of testing fluidfrom the conduit means and being designed to convert the stream into acoherent jet or flow, means defining an intercepting orifice located inthe path of the coherent flow and serving to convey the flow to thetesting station, and means defining a chamber which communicates withthe atmosphere and through which the coherent flow advances withclearance on its way from the injector nozzle into the orifice. Thetesting apparatus further comprises an electropneumatic transducer orother suitable signal generating means for monitoring the aforementionedpressure differential between the interior and the exterior of thewrapper at the testing station.

The diameter of the chamber exceeds the diameter of the outlet end ofthe passage which is defined by the injector nozzle and also thediameter of the intercepting orifice, i.e., the coherent flow traversesthe chamber without any guidance during propagation from the nozzletoward and into the intercepting orifice.

The orifice defining means can comprise a stationary valve member whichpreferably supports the nozzle as well as the chamber defining means andis adjacent to one end of the wrapper at the testing station. Such valvemember is formed with a suitably configurated groove or analogous meansfor admitting testing fluid into the adjacent end of the wrapper whilethe respective article advances past the testing station.

The diameter of the inlet portion of the passage which is defined by theinjector nozzle preferably diminishes in a direction from the conduitmeans toward the chamber, and the length of the passage which is definedby the injector nozzle is preferably selected in such a way that theflow issuing from the nozzle is a laminar flow which is free ofturbulence.

The apparatus can comprise second conduit means which also receives astream of testing fluid from the aforementioned source and serves toconvey such fluid toward the other end of the wrapper which advancespast the testing station. Such apparatus can comprise second oscillationpreventing means which is interposed between the second conduit meansand the testing station to prevent oscillations of testing fluid in thesecond conduit means.

Still further, the apparatus can comprise additional conduit means whichconveys testing fluid between the interior of a wrapper at the testingstation and the monitoring means or which conveys to the monitoringmeans testing fluid whose pressure has been influenced by the conditionof the wrapper at the testing station. Such apparatus can compriseadditional oscillation preventing means which is associated with theadditional conduit means.

The injector nozzle can be mounted in such a way that it is coaxial withthe chamber defining means, with the orifice defining means as well aswith the wrapper at the testing station.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved testing apparatus itself, however, both as to its constructionand its mode of operation, together with additional features andadvantages thereof, will be best understood upon perusal of thefollowing detailed description of certain specific embodiments withreference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a fragmentary partly diagrammatic and partly axial sectionalview of a testing apparatus wherein the development of oscillations inthe column or columns of testing fluid is prevented or reduced inaccordance with the present invention; and

FIG. 2 an enlarged view of a detail in the upper left-hand portion ofFIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to FIG. 1 there is shown a portion of a testingapparatus for filter cigarettes 3 each of which includes an elongatedtobacco-containing portion or plain cigarette 7 and a filter 8 which isconnected to the right-hand end portion of the plain cigarette 7 by auniting band, not specifically shown. The cigarette 3 is held in anaxially parallel peripheral flute 2 of a rotary drum-shaped testingconveyor 1 which rotates about an axis extending in parallism with theaxis on the cigarette 3. The means for driving the conveyor 1 at thespeed of other moving parts in a filter tipping machine is notspecifically shown in the drawing. Reference may be had to commonlyowned U.S. Pat. No. 3,948,084 granted Apr. 6, 1976 to Heitmann et al.The disclosure of this patent is incorporated herein by reference. Themachine in which the testing apparatus of the present invention isinstalled can be a machine of the type known as MAX-S manufactured andsold by the assignee of the present invention. Machines of such type aredescribed, for example, in commonly owned U.S. Pat. No. 4,281,670granted Aug. 4, 1981 to Heitmann et al. The disclosure of this patent isalso incorporated herein by reference.

The periphery of the testing conveyor 1 has several equidistant flutes 2each of which can carry a discrete cigarette 3 toward, past and beyondthe testing station which is shown in the upper part of FIG. 1. Eachflute 2 contains two raised portions or projections 4 having small endfaces one of which is in contact with the wrapper of the respectiveplain cigarette 7 and the other of which is in contact with the wrapperof the respective filter 8. The projections 4 are formed with suctionports 6 which are connected with a suction generating device (notspecifically shown) so as to ensure that the cigarettes 3 are held intheir flutes 2 during transport toward, past and beyond the testingstation. Such cigarettes are admitted into the respective flutes 2 by acigarette feeding conveyor at one side of the testing station, andsuccessive tested cigarettes are removed from their flutes 2 at theother side of the testing station to enter the flutes of a furtherconveyor, not shown. The area of contact between each projection 4 andthe respective cigarette 3 is small or very small in order to ensurethat such projections will not accidentally seal holes, portions of openseams or other types of defects in the wrappers of articles advancingpast the testing station.

The left-hand end portion of the conveyor 1, as viewed in FIG. 1, isformed with a collar or flange 9 which extends radially outwardly beyondthe adjacent projections 4 and is formed with axially parallel bore 11the right-hand ends of which are sealed by the left-hand end faces ofcigarettes 3 in the respective flutes 2. The right-hand end portion ofthe conveyor 1 is also formed with a radially outwardly extending collaror flange 12 having an annulus of axially parallel bores 19 each ofwhich constitutes a socket for a reciprocable sealing nipple 14. Eachsocket 19 is in register with one of the bores 11 in the left-handflange 9 of the conveyor 1. The illustrated nipple 14 is biased in adirection to the left, as viewed in FIG. 1, by a coil spring 13 whichreacts against the flange 12 and bears against the larger-diameterleft-end portion of the nipple. The end face 18 of the nipple 14 abutsagainst the adjacent cigarette 3 so that the right-hand end face of suchcigarette seals the corresponding end of an axial passage or bore 17 inthe nipple 14. The sleeve 16 of the nipple 14 is reciprocable, withnegligible play, in the respective socket 19 of the flange 12. Thenipple 14 is depressed into the socket 19 against the opposition of thecoil spring 13 when the corresponding flute 2 is to discharge a freshlytested cigarette 3 and when such flute is to receive an untestedcigarette for transport toward, past and beyond the testing station.

The frame or housing in which the conveyor 1 is rotatably mountedincludes a stationary shoe or valve plate 21 which is outwardly adjacentto and abuts against the exposed end face of the flange 12. The shoe 21has a nipple 22 which is connected with a source 27 of compressedtesting fluid by a conduit 26. The discharge end of the nipple 22communicates with a bore 23 which is machined into the valve plate 21and which further communicates with a groove 24 provided in that endface of the valve plate 21 which abuts against the adjacent end face ofthe flange 12 so that the groove 24 communicates with successive sockets19 of the flange 12 when the conveyor 1 rotates to advance successivecigarettes 3 toward, past and beyond the testing station. The groove 24further communicates with a transducer 31 by way of a bore 28, which ismachined into the valve plate 21, and a conduit 29. The transducer 31can constitute a conventional electro-pneumatic transducer whichconverts pneumatic signals into corresponding electric signals. Suchsignals are thereupon processed and utilized for segregation ofdefective cigarettes 3 from satisfactory cigarettes in a manner notforming part of the present invention. For example, each such signal canbe compared with a reference signal which is indicative of asatisfactory cigarette; when the difference between the signal which isgenerated by the transducer 31 and the reference signal exceeds acertain value, the corresponding cigarette is considered to be defectiveand is segregated from satisfactory cigarettes.

The left-hand flange 9 of the conveyor 1 is adjacent to a secondstationary valve plate or shoe 32 having a groove 33 machined into thatend face thereof which abuts against the conveyor 1. The groove 33communicates with successive bores 11 of the flange 9 when the conveyor1 is in rotary motion. This groove is connected with a second outlet ofthe source 27 of compressed testing fluid by a second conduit 36 throughthe medium of an injector nozzle 37 and a hollow cylindrical element 43defining a chamber 38 which is in communication with the groove 33 ofthe valve plate 32 by an intercepting orifice 34. The cylindricalelement 43 is formed with an annulus of venting openings 39 whichconnect the chamber 38 with the surrounding atmosphere. The injectornozzle 37 comprises a conically converging inlet portion 41 and acylindrical flow restricting portion 42 defining a channel having adiameter which is less than the diameter of the chamber 38 and matchesthe diameter at the discharge end of the passage in the inlet portion41.

The mode of operation of the testing apparatus which is shown in FIGS. 1and 2 is as follows:

It is assumed that the wrapper of the cigarette 3 which is shown in FIG.1 is provided with a set of venting holes or pores which are supposed topermit a certain flow of cool atmospheric air into the interior of thecigarette to mix with the column of hot tobacco smoke when the cigaretteis lighted. The conveyor 1 is in motion, and successive flutes 2 receivefilter cigarettes 3 of unit length at the upstream side of the testingstation shown in FIG. 1. Each cigarette 3 is inserted into therespective flute 2 while the corresponding sealing nipple 14 isretracted (for example, by a stationary cam) against the opposition ofthe corresponding coil spring 13 so that the space between the flange 9and the retracted nipple 14 suffices for convenient insertion of anuntested cigarette into the respective flute 2. The cam thereuponpermits the coil spring 13 to expand and to move the end face 18 of thenipple 14 against the respective end of the cigarette 3 which isattracted to the conveyor 1 by suction in the ports 6 extending into theprojections 4. The coil spring 13 thereby pushes the cigarette 3 againstthe flange 9 so that the left-hand end of the cigarette communicateswith the bore 11 in the flange 9 while the right-hand end of suchcigarette communicates with the passage 17 of the nipple 14. Theconveyor 1 receives filter cigarettes 3 of unit length at the rate atwhich such cigarettes are formed in the filter tipping machine.

A properly inserted cigarette 3 assumes the position which is shown inFIG. 1 not later than when the corresponding flute 2 reaches the testingstation between the groove 33 of the stationary valve plate 32 and thegroove 24 of the stationary valve plate 21.

When the cigarette 3 arrives at the testing station, the bores 11 and 17begin to communicate with the respective grooves 24 and 33 so thatstreams of compressed testing fluid flow from the respective conduits26, 36 into the corresponding ends of the wrapper of the cigarette 3 atthe testing station. The conduit 26 admits testing fluid into the nipple22 whereby such fluid flows through the bore 23 and into the groove 24whence the fluid flows into the socket 19 and thence into the passage orbore 17 when the corresponding nipple 14 reaches the testing station.The conduit 36 continuously admits testing fluid into the groove 33whence the fluid flows into the left-hand end of the cigarette 3 whensuch cigarette reaches the testing station because the correspondingbore 11 then communicates with the groove 33.

Since the speed of the conveyor 1 in a modern filter tipping machine isextremely high (as mentioned above, such machines can turn out well inexcess of one-hundred filter cigarettes per second), the testing fluidis abruptly admitted into both ends of the wrapper of the cigarette 3which reaches the testing station. Consequently, the pressure of testingfluid in the conduits 26 and 36 drops drastically when some of thetesting fluid is permitted to flow into the interior of the wrapper ofthe cigarette 3 at the testing station. Such rapid drop of pressure ofthe testing fluid normally results in oscillations of the columns of airin the conuits 26, 36 as well as in the conduit 29 which latter connectsthe groove 24 with the transducer 31. Consequently, and in order toensure that the signal which is generated by the transducer 31 duringpassage of a cigarette 3 through the testing station will be a reliableindicator of the condition of the respective cigarette (namely, of thepermeability of the wrapper to atmospheric air which is to flow into thecolumn of hot tobacco smoke when the cigarette is lighted), it isdesirable to await the termination or dying out of oscillations of thecolumn or columns of air in the aforementioned conduits 26, 36 and 29.This can take up a reasonably long interval of time, namely, asubstantial part of that interval which is allotted for the testing ofsuccessive cigarettes 3 at the testing station. As mentioned before,these intervals are extremely short (normally in the range of a fewmilliseconds) so that any shortening of such intervals for the purposeof preventing oscillations of the air column or columns from influencingthe quality of the testing operation could adversely affect the testingoperation. In other words, postponements of the generation of testingsignals until after the oscillations of the air columns have faded outin conventional testing apparatus greatly reduce the length of thoseintervals which remain available for the actual testing operation.

It has been found that the arrangement which is shown in the left-handportion of FIG. 1 and, on a larger scale, in FIG. 2 of the drawing iscapable of effectively eliminating or greatly reducing the extent andduration of oscillations of air columns in various conduits,particularly in the conduit 36 which connects the source 27 ofcompressed testing fluid with the groove 33 of the stationary valveplate 32. This arrangement, designated by the reference charecter 44,includes the aforementioned injector nozzle 37 and the parts whichdefine the chamber 38 and the intercepting orifice 34 leading from thechamber 38 into the groove 33 of the stationary valve plate 32. Thestream of testing fluid which issues from the source 27 and flowsthrough the conduit 36 enters the conically converging inlet portion 41of the injector nozzle 37 on its way into and through the cylindricalflow restricting portion 42 before entering the larger-diameter chamber38. The provision of the cylindrical portion 42, whose inner diameter isa relatively small fraction of the diameter of the chamber 38, ensuresthat the flow of testing fluid entering the chamber 38 is laminar.Furthermore, such flow is without any turbulence. The length of theconical inlet portion 41 and of the cylindrical portion 42 of theinjector nozzle 37 can be readily selected in such a way that theturbulence at the outlet of the nozzle 37 is negligible or non-existent.Consequently, the air stream which leaves the cylindrical portion 42 ofthe injector nozzle 37 constitutes a strongly coherent laminar jet ofgaseous fluid which passes, without any guidance, through the chamber 38to enter the groove 33 via orifice 34. The inlet of the orifice 34 is inregister with the passage of the cylindrical portion 42 of the injectornozzle 37. This ensures that the entire laminar and turbulence-free jetof testing fluid enters the orifice 34 on its way into the groove 33 ofthe stationary valve plate 32. Such testing fluid then enters thecorresponding end of the cigarette 3 as soon as the respective bore 11of the flange 9 reaches the testing station.

The other end of the wrapper of the cigarette 3 at the testing stationsimultaneously receives a stream of testing fluid via conduit 26, nipple22, bore 23, groove 24, socket 19 and passage 17. This marks thebeginning of the testing operation. During testing, the pressure oftesting fluid in the groove 24 (such pressure changes abruptly when theends of the wrapper at the testing station begin to communicate with thegrooves 24 and 33) is communicated to the transducer 31 via conduit 29whereby the transducer generates a signal which is indicative of thecondition of ventillating pores or holes in the wrapper of the cigarette3. If desired, an in order to further improve the result of the testingoperation, the transducer 31 can be mounted directly in or on the valveplate 21.

The pressure in the grooves 24 and 33 again changes abruptly as soon asa cigarette 3 advances beyond the testing station, namely, as soon asthe bores 11 and 19 move out of register with the corresponding grooves24 and 33. Such abrupt changes of pressure in the grooves 24 and 33 canagain cause oscillations of the columns of air in the conduits 26, 36and 29. The oscillations are effectively reduced or eliminated by theprovision of the arrangement 44 including the injector nozzle 37 and theparts defining the chamber 38 and orifice 34. It has been found thatsuch arrangement reliably reduces the oscillations, or eliminates suchoscillations altogether, so that the entire or substantially entireinterval of travel of a cigarette 3 through the testing station can beused for ascertainment of the condition of the wrapper of suchcigarette. It has also been found, that the arrangement 44 preventsoscillations of the column of air in the conduit 36 even when theconveyor 1 is driven at a high or very high speed, such as is requiredin the aforediscussed modern high-speed filter tipping or analogousmachines. Consequently, the signals which are generated by thetransducer 31 are not influenced by oscillations of the air column inthe conduit 36 because such oscillations cannot develop at all or arenegligible. Moreover, and as already mentioned above, the absence ofoscillations renders it possible to utilize the entire interval oftravel of a cigarette 3 through the testing station for the generationof a reliable signal which is thereupon processed and used to expel orsegregate defective cigarettes from satisfactory cigarettes on their waytoward the next processing station, e.g., during travel of filtercigarettes from the filter tipping to the packing machine. It will bereadily appreciated that the reliability of the transducer 31 and of theentire testing apparatus is greatly increased in the entire intervals oftravel of cigarettes through the testing station can be used forgeneration of appropriate test signals.

As mentioned above, the arrangement 44 is installed between the source27 of compressed testing fluid and the left-hand groove 33 of FIG. 1,namely between the conduit 36 and the valve plate 32. It goes withoutsaying that this apparatus can comprise a second oscillation eliminatingor preventing arrangement which is installed (at 144) between theconduit 26 and the groove 24, as well as an additional arrangement whichcan be installed (at 244) between the groove 24 and the transducer 31.This further reduces the likelihood of adverse influence of oscillationsof columns of testing fluid in response to rapid changes in pressure ofsuch fluid as a result of abrupt arrival of cigarettes at and abruptdeparture of cigarettes from the testing station.

As also mentioned above, the improved testing apparatus can be used withadvantage in filter tipping machines, namely, in machines wherein plaincigarettes, cigarillos or cigars are united with filter mouthpieces toform filter cigarettes, cigars or cigarillos of unit length or multipleunit length. Of course, such testing apparatus can be used with equal orsimilar advantage in other types of tobacco processing and analogousmachines, for example, in machines for the production of plaincigarettes. Furthermore, the testing apparatus need not be utilizedexclusively for detection of the condition of so-called aerating zonesin the filter mouthpieces or tobacco containing portions of filtercigarettes or the like. Such testing apparatus are equally useful fordetection of open seams, frayed ends of and/or holes in the wrappers ofplain cigarettes, cigars, cigarillos or filter rod sections. In fact,the improved testing apparatus can be utilized in all such machineswherein the frequency of testing is sufficiently high to causeundesirable oscillations of the column or columns of testing fluid as aresult of abrupt delivery of articles to and abrupt transport ofarticles from and beyond the testing station.

There is no need to guide the laminar air jet on its way through thechamber 38 of the oscillation-eliminating arrangement 44. Such laminarflow is sufficiently coherent to ensure that it passes through thechamber 38 and enters the groove 33 of the valve plate 32 by way of theorifice 34. The entire arrangement 44 can be mounted directly on thestationary valve plate 32 or on another portion of the means forsupporting the rotary conveyor 1.

It is believed that free transfer of testing fluid in the form of acoherent laminar flow from the injector nozzle 37, through the chamber38, and into the orifice 34 (such orifice can form part of a transducerwhich replaces the transducer 31) is the reason for elimination orreduction of intensity of oscillations of the column of testing fluid inthe conduit 36. The conicity of the passage in the inlet portion 41 ofthe injector nozzle 37 contributes to the formation of a highlydesirable coherent laminar flow of air which advances into and throughthe chamber 38 wherein the pressure matches atmospheric pressure.

Another important advantage of the improved testing apparatus is that itallows for further increase of the frequency at which the cigarettes aretested, for example, by reducing the available intervals of time foreach testing operation. This is desirable and advantageous in connectionwith further development of presently known filter tipping and similarmachines wherein the trend continues to be toward higher output, i.e.,toward an output which is even in excess of the presently availableoutputs. Still another advantage of the improved testing apparatus isthat the elimination of oscillations of the column of testing fluid inthe conduit 36 (and in the other conduits if such conduits are alsoequipped with the improved oscillation eliminating arrangement) isachieved in an extremely simple and inexpensive way. The provision ofinjector nozzle 37 and of means defining the chamber 38 and orifice 34constitutes a negigible expense when compared with the cost of a modern,high-speed filter tipping or like machine. Furthermore, such arrangementis extremely reliable and requires little or no attention so that it canbe utilized for long periods of time without requiring cleaning,inspection or replacement. The bulk of the improved testing apparatusdoes not exceed the bulk of conventional testing apparatus so that theimproved apparatus can be readily installed in existing filter tippingor like machines as a superior substitute for conventional testingapparatus.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic and specific aspects of my contributionto the art and, therefore, such adaptations should and are intended tobe comprehended within the meaning and range of equivalence of theappended claims.

I claim:
 1. Apparatus for testing at a testing station the open-endedtubular wrappers of cigarettes or analogous rod-shaped articles whereinthe wrapper surrounds a filler of tobacco and/or filter material,comprising conveyor means arranged to transport a succession of articlestoward, past and beyond the testing station; means for admitting astream of gaseous testing fluid into at least one end of the wrapperforming part of the article advancing past the testing station withattendant establishment of a pressure differential between the interiorand the exterior of the wrapper, including a source of gaseous testingfluid, conduit means for conveying a stream of testing fluid from saidsource toward the testing station, and means for preventing oscillationsof testing fluid in said conduit means as a result of abrupt admissionand/or abrupt termination of admission of testing fluid into thewrappers of articles at the testing station, said oscillation preventingmeans comprising an injector nozzle receiving the stream of testingfluid from said conduit means and arranged to convert such stream into acoherent flow, means defining an intercepting orifice located in thepath of said coherent flow and arranged to convey such flow to thetesting station, and means defining a chamber which communicates withthe atmosphere and through which the coherent flow advances withclearance on its way from said nozzle toward and into said orifice; andsignal generating means for monitoring said pressure differential. 2.The apparatus of claim 1, wherein the diameter of said chamber exceedsthe diameter of said orifice.
 3. The apparatus of claim 2, wherein saidnozzle defines a passage having an outlet end whose diameter is lessthan the diameter of said chamber.
 4. The apparatus of claim 1, whereinsaid orifice defining means includes a stationary valve member adjacentto one end of the wrapper at the testing station and including means foradmitting testing fluid into such end of the wrapper during travel ofthe respective article past the testing station.
 5. The apparatus ofclaim 4, wherein said nozzle amd said chamber defining means are mountedon said valve member.
 6. The apparatus of claim 1, wherein said nozzledefines a passage having an inlet portion whose diameter decreases in adirection from said conduit means toward said chamber.
 7. The apparatusof claim 1, wherein said nozzle defines a passage for testing fluid, thelength of said passage between said conduit means and said chamber beingsuch that the stream is converted into a laminar flow.
 8. The apparatusof claim 1, further comprising second conduit means receiving a streamof testing fluid from said source and arranged to convey such fluidtoward the other end of each wrapper at the testing station, and secondoscillation preventing means interposed between said second conduitmeans and the testing station.
 9. The apparatus of claim 1, furthercomprising additional conduit means arranged to convey testing fluidbetween the interior of a wrapper at the testing station and saidmonitoring means, and additional oscillation preventing meanscommunicating with said additional conduit means.
 10. The apparatus ofclaim 1, wherein the testing fluid is air.
 11. The apparatus of claim 1,wherein said nozzle is coaxial with said chamber and with said orifice.